![]() ![]() ) All species are tolerant of a wide range of soils and pH levels but, with few exceptions, demand good drainage. (Very rarely anomalous samarae occur with more than two wings. The samarae are very light, those of British elms numbering around 50,000 to the pound (454 g). The fruit is a round wind-dispersed samara flushed with chlorophyll, facilitating photosynthesis before the leaves emerge. Elm leaves are alternate, with simple, single- or, most commonly, doubly serrate margins, usually asymmetric at the base and acuminate at the apex. The genus is hermaphroditic, having apetalous perfect flowers which are wind-pollinated. 4.2.1 Cautions regarding novel cultivars.In response, disease-resistant cultivars have been developed, capable of restoring the elm to forestry and landscaping. However, in recent decades, most mature elms of European or North American origin have died from Dutch elm disease, caused by a microfungus dispersed by bark beetles. Some individual elms reached great size and age. Moreover, during the 19th and early 20th centuries, many species and cultivars were also planted as ornamental street, garden, and park trees in Europe, North America, and parts of the Southern Hemisphere, notably Australasia. ![]() ![]() Įlms are components of many kinds of natural forests. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical- montane regions of North America and Eurasia, presently ranging southward in the Middle East to Lebanon and Israel, and across the Equator in the Far East into Indonesia.
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